Tool and method for its manufacture

ABSTRACT

A method is disclosed for manufacturing a tool or a part thereof for carrying out operations such as pressing, cutting, hemming and the like, and in which the tool is given different material properties in different parts of the tool, wherein the tool is cast to one united piece, the casting material with at least two different material properties being supplied, one to each of the different parts of the tool, and at least one of the casting materials being supplied in liquid form.

TECHNICAL FIELD

The present invention relates to a tool or a part thereof for carryingout operations such as pressing, cutting, hemming and the like andincludes at least a first and a second tool part with differentfunctions in the tool, for example a tool body amid an functional partdisposed thereon in order, alone or together with some other additionalfunctional part, or additional tool, to carry out the operation, thefirst-and the second parts possessing different material properties.

The present invention also relates to a method for manufacturing a toolor a part thereof, for carrying out operations such as pressing,cutting, hemming and the like, and entails that the tool is givendifferent material properties in different parts of the tool.

BACKGROUND ART

In the manufacture of a tool for the above-outlined purpose, it haspreviously been the practice to separately manufacture a tool body whichsubsequently, ill the example of a cutting tool, is provided with one ormore cutters. The manufacture of the tool body may be put into effect bycasting or by welding on the basis of suitably dimensioned sheetmaterial of appropriately adapted material composition

In the case of a cast tool body, this often requires heat treatmentafter the casting, whereafter machining is put into effect in order toobtain the requisite seats, guide pins and bolt holes for securing thecutters, but also in order to make possible securing of the tool body ina machine.

Correspondingly, in the alternative of welding of the tool body,extensive machining is required in order to be able to secure one ormore cutters on the tool body and in the correct position, and in orderto be able to secure the tool in a machine.

In the manufacture of the functional part or parts, in theabove-disclosed example the cutters, which are intended for carrying outthe. operations for which the tool has been designed, the point ofdeparture has previously often been rod or bar material in which eventthe functional parts, in this example the cutters, are machined to thecorrect configuration, provided with apertures and anchorage bolts,guide pins and the like. This is often followed by a heat treatment,whereafter further machining such as, for example, grinding, is put intoeffect

To manufacture a tool in the above-outlined maimer is extremelytime-consuning and such manufacture is, as a result, often determinativeof the time consumption required in the new manufacture of differentproducts.

It is also previously known in the art, in the manufacture of tools bywelding, flash welding and similar methods, to apply a material of adifferent composition, for example to a tool body so that a functionalpart is formed thereon. By such means, a tool will be obtained whichconsists of a single material piece, but in which the materialcomposition in different parts thereof differs.

Also in this alternative, extensive machining is required, for examplein the form of joint preparation in welding and after-treatment of aweld before additional welding material can be applied When the materialapplication is completed, further machining is required, possibly alsoheat treatment and subsequent grinding before the tool is ready to bemade operational.

When a tool has become obsolescent, for example because the part whichis produced in the tool has itself become obsolete, or because the toolhas quite simply become worn out the entire tool is scrapped, eventhough the tool body could very well be re-used. This naturally entailsa waste of material, time and money.

Problem Structure

The present invention has for its object to obviate the drawbacksinherent in the prior art technology. Principally, the present inventionhas for its object to shorten the production time for a tool, but alsoto minimise the need of machining in the manufacture of the tool and tomale possible the retro-construction of an obsolescent tool.

Concerning the tool, the present invention has for its object to designthe tool or a part thereof such that different parts of the tool displaydifferent material compositions adapted so as to impart to the differentparts their intended material properties.

Concerning the method, the present invention has for its object topropose a method for the manufacture of a tool or a part thereof inwhich different parts of the tool may be given different materialcompositions and, consequently, different material properties.

Solution

The objects forming the basis of the present invention will be attainedconcerning the tool is this is characterised in that the first and thesecond tool parts are cast in one united piece and that they possessdifferent material compositions.

The objects forming the basis of the present invention will be attainedconcerning the method if this is characterised in that the tool is castin one united piece, the casting material of at least two differentmaterial compositions being supplied to the different parts of the tooland at least the one casting material being supplied in liquid form.

BRIEF DESCRIPTION OF TEE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detailhereinbelow, with reference to the accompanying Drawings. In theaccompanying Drawings:

FIG. 1 is a cross section through a part of a tool, in this case acutting tool;

FIG. 2 is a partial cross section, on a larger scale, through a partmarked by means of the arrow A of the tool of FIG. 1; and

FIG. 3 is a cross section through a mould for manufacturing a toolaccording to the present invention,

DESCRIPTION OF PREFERRED EMBODIMENT

In FIG. 1, reference numeral 1 relates to a machine bed or foundation onwhich the tool 2 is secured by means of a bolt union 3.

The tool illustrated ill FIG. 1 by way of example is a cutting toolwhich is in two parts and consists therefore of two tool parts, a lowertool part 2 and an upper tool part 4. The tool parts 2 and 4 are,however, in this context considered as separate tools.

A tool may be thought of as being composed of a plurality of differentcomponents, for example a tool body and a functional part d theillustrated example, the functional part would consist of a cutter whichis intended to carrying out the processing operation together with acorresponding functional part on the upper tool 4.

In FIG. 1, the tool 2 includes a tool body 5 which has a lower mountingplate 6 for securing the tool on the tool table or bed 1. Further, thetool body 5 includes an upper part 7 which, in the illustratedembodiment, has rigidification ribs 17. The upper part 7 is connected tothe anchorage plate 6 by the intermediary of a wall portion 8.

The tool 2 illustrated in FIG. 1 has a functional part 9 which isintended to realise the cutting operation proper and which is supportedby and is of one piece manufacture with the tool body 5. The functionalpart 9 has an edge 10, a flank or rake 11 and a surface 12 on which theworkpiece is supported during a cutting operation.

Correspondingly, the upper tool 4 has a functional part 13 with an edge14, a flank or rake 15 and a surface 16 for abutment against theworkpiece.

When the tool is in operation, the workpiece rests on the tool 2, inparticular on its upwardly facing surface 12, and extends more or lessoutside the edge 10 in a direction to the right in FIG. 1. in oneworking stroke, the upper,tool 4 moves according to the arrow B so fardown that the edge 14 passes down to or slightly past the edge 10. Thus,during the working operation, it is both of the functional parts 9 and13 that realise the working operation, in this case the cuttingoperation.

It will readily be perceived that the two edges 10 and 14, as well asurrounding parts of the tools, must display superior mechanicalstrength, both toughness and hardness, as well as in addition an abilityto produce relatively sharp edges. This is a requirement which the toolbody 5 by no means needs to satisfy but, as regards the tool bodyproper, it is properties such as, for example, vibration damping andslight outward flexing which are more important than those propertiesthat are required for carrying out the wL g operation itself For thisreason, both of the functional parts 9 and 13 possess totally differentmaterial properties than does the tool body 5.

In actual fact, different material properties could be achieved in atool which, in its entirety, consists of one and the same material, butin which different parts of the tool are treated in different ways, forexample by heat treatment. However, this implies a limitation in thosedifferences in material properties that may be attained and, on theother hand, unnecessary costs since probably one material which isappropriate for one functional part may be considered as overqualifiedin a tool body.

According to the present invention, those parts of a tool which, becauseof different functional requirements, possess different materialproperties, also have a different composition of the material lyingbehind the different material properties.

In the manufacture of a tool according to the present invention, this iscast from at least two different casting materials of different materialcompositions into one united piece. The term casting is taken to signifythat a liquid carrying material is supplied into a mould where the castmaterial is allowed or caused to harden into a casting whose form isdefined by the form of the mould cavity which is enclosed in the mouldThe casting operation may be put into effect such that a clear and sharpinterface between the different casting materials is achieved, oralternatively the casting operation may be put into effect so that acertain intermingling of the two casting materials takes place in aninterface zone.

In the casting operation so that a sharply defined interface occurs, thefirst cast part of the tool is allowed to harden so far that nointermingling of the casting materials occurs. Alternatively, use may bemade of a tool part which is cast in a separate process or which hasbeen recovered and recycled from at old, obsolete tool and which, in theheated state (600-750° C.) is inserted in a mould where an additionaltool part is cast or

In the casting so that an interface zone is formed between the toolparts, the hardening and cooling of the first cast tool part is allowedto continued only so far that a limited intermingling of the castmaterials can take place or that a certain remelt of the already casttool part can take place. The positive cooling or rest cooling of thecast material which was cast first may also be put into effect in adirected fashion, so that a hardening zone migrates through the castingand finally arrives at that side of the tool part where the additionalcasting-on is to take place.

In casting according to the present invention, sand foundry casting isoften employed where the mould cavity at the beginning of the castingoperation is filled by a template or model which is broken down andvaporised on the supply of the hot and liquid casting material. Themodel can, for example, be produced from expanded polystyrene. Thematerial from the model floats up on the casting material and isaccumulated uppermost on it where it may cause local deterioration inquality in the casting material. For this reason, the mould is orientedin such a manner and the tool parts are cast in such a sequence that thelocal deterioration in quality will have as slight consequences aspossible. In particular, it is to be ensured that the localdeterioration in quality of the casting material is located at adistance from the functional surface of the functional parts, i.e. thatsurface on the tool which carries out the functional proper of the tool.

FIG. 2, which shows a partial magnification of the functional part 9 andthereby the area A of the tool 2 in the proximity of the edge 10, showsa dotted area 18 and a dashed area 19 where the two areas 18 and 19display different material compositions. In FIG. 2, the interfacebetween the two areas 18 and 19 is clearly marked and can, in apractical version, amount to an extremely thin interface layer or stratabetween the two areas.

However, if a more continuous transition between the areas 18 and 19 isdesirable, it is possible in the manufacture of the tool, tointermingle, in an interface zone between the areas 18 and 19, both ofthe different materials from the areas 18 and 19.

FIG. 2 further shows a third area 20 which, in the Drawing, is marked byringlets. This third area 20 is thereby intended to have yet another,third material composition and consequentially different materialproperties than those possessed by the functional parts in the areas 18and 19. For example, the area 20 marked by the ringlets may consist of arelatively cheap material which is employed for the greater part of thetool body 5.

In order to ensure that at least the functional part 9 possessesaccurately Controllable material properties, use is made of a castingmaterial in granulate form and of high purity, as well as an analysis ofsmall tolerances.

Those parts 9 and 13 of the tool which carry out the working operationproper, the functional parts, should possibly undergo, after the castingoperation, a minor machining operation to the intended tolerances andgrinding finish Possibly, these parts may also be heat treated so thatthe material properties will be those intended in the end product.Correspondingly, the functional parts may be provided with a coating ofa material comprising yet a further different composition.

FIG. 3 shows a vertical cross section through one example of a mouldwhich may be employed for the production of a tool according to thepresent invention. In the Figure, the tool is shown as ready-cast in theinverted state and it will be apparent that the tool has an anchorageplate 6, side walls 8 and an upper region 7. The previously named partsof the tool may be considered as a tool body which, for example, may becast in a material of relatively low quality,

In its upper region (that turned to ice downwards in the Figure), thetool has a functional part 9 which is cast from a material possessingdifferent composition than the tool body and which has those propertiesthat are needed in the functional surface 21 of the tool, i.e. thatsurface which produces the forming function of the tool.

It will further be apparent from the Drawing that there is an interfacezone between the fictional part 9 and the tool body where,the two castmaterials meet one another.

Before the casting of the tool according to FIG. 3, it may be assumedthat the mould cavity of the mould was filled by a model or templateconsisting of expanded polystyrene. In the casting, the material forforming the functional part 9 is first cast from the ladle 22 down intothe gate 23 of the mould. In this instance, the hot and molten castingmaterial will vaporise and break down Cat part of the model which is incontact with the casting material. This material thus finds nodifficulty in penetrating through the model and in arriving at the lowersurface of the mould where the functional surface 21. of the tool isformed. The degradation products from the model float upwards on thecasting material and, as a result, may possibly bring about a localdeterioration in the quality therein.

When the functional part 9 has been cast and allowed to harden wholly orpartly, depending on the desired interface zone between the functionalpart and the tool body, the material for forming the tool body issupplied via the gate 23. It this instance, remaining parts of the modelwill be broken down and vaporised as well as float upwards in the mould.The local deterioration of the material quality which the material ofthe model per se may possibly cause will, as a result, arrive uppermostin the mould, i.e. in the anchorage plate 6 of the tool where anypossible deterioration in quality will have as slight consequences aspossible.

The present invention also embodies the possibility that an existing butobsolescent tool may at least partly be recycled and reused. In thisinstance, the existing tool is cleaned, whereafter its functional partis removed, e.g. by being milled or ground off. A fully usable tool bodywill remain, which is to be provided with a new functional part.

The functional part may be realised in that a block of expandedpolystyrene is secured to the processed tool body, whereafter a templateor model for the functional part is formed by the blocks Thereafter, amould is produced which on the one hand encloses a mould cavity for thenew functional part and on the other hand at least a part of the oldtool body, the tool body being located uppermost and the mould cavitylowermost The mould has a gate whose lower end discharges in theinterice zone between the tool body and the mould cavity. Possibly, themodel or template may be left in place in the mould cavity.

On casting of the new functional part, if the model is still in place inthe mould cavity, it will be vaporised and the residue will float up onthe casting material. This implies that any possibly negative effect onthe casting material which may be caused by the residual products fromthe model will be located a distance from the working surface of thefunctional part and, more precisely, m an interface zone between the oldtool body and the new functional part

On casting a new functional part on an old tool body, it is crucial thatthe tool body be heated to a temperature suitable for casting on, oftenof the order of magnitude of 650-700° C., As a result, the mould isprovided with a heating device. Alternatively, the tool body may beprovided with a heating device or be pre-heated beforehand.

Once the casting of the new functional part is finished, the tool isremoved from the mould and the functional part cleaned and sand blastedThereafter, possible later heat treatment and fine-adjustment of theworking surface way be put into effect.

1-4. (canceled)
 5. A method of manufacturing a tool or a part thereoffor carrying out operations such as pressing, cutting, hemming and thelike, and in which the tool is given different material properties indifferent parts of the tool, characterised in that the tool is cast toone united piece, the casting material with at least two differentmaterial properties being supplied, one to each of the different partsof the tool, and at least one of the casting materials being supplied inliquid form.
 6. The method as claimed in claim 5, characterised in that,in the casting operation of the tool, casting materials of differentcompositions are kept separate and discrete from one another.
 7. Themethod as claimed in claim 5, characterised in that, in the casting ofthe tool, casting materials of different compositions are intermingledin a zone between parts of the tool, where the material compositiondiffers.
 8. The method as claimed in claim 5, characterised in that atleast one of the tool parts is at treated.
 9. The method as claimed inclaim 5, characterised in that at least one of the tool parts isprovided with a surface coating.